1. Field of the Invention
The present invention relates to an improved structure of a carriage module, and especially to a carriage module used inside a machine of an optical pickup device.
2. Description of the Related
In general, the carriage module is used by the optical pickup device as a scanner, a copy machine or a MFP (Multi-Function Printer) for scanning documents and transferring an optical image thereof into an electric signal. FIG. 1 shows a perspective view of the carriage module of the prior art. Referring to FIG. 1, the carriage module 9 is moved in a reciprocating, straight-line motion along an axle shaft 91 for picking up an image of the scanned document. The carriage module 9 of the prior art usually comprises a linear light-source 92, a carriage top cover 93, a plurality of reflecting mirrors (FIG. 1 just shows a first reflecting mirror 94), a carriage bottom seat 95, a condensing device 96 and a photoelectric transforming device 97.
The linear light-source 92 is usually a light tube for providing light. The light is reflected from the document to the reflecting mirrors. The condensing device 96, usually a lens set, receives the reflected light that is reflected from the reflecting mirrors and then condenses the reflected light to form an image on the photoelectric transforming device. The photoelectric transforming device is usually a CCD (charge-coupled device) for transforming a photo image into an electric signal. Final, the electric signal is transformed into a digital signal by an A/D converter and digital signal is communicated to a computer by a plurality of different interfaces.
With regard to the assembly of the carriage module, the parts of the carriage module are assembled on the carriage top cover 93 and the carriage bottom seat 95 with a concave receiving space, respectively. Moreover, the carriage top cover 93 and the carriage bottom seat 95 are assembled together. Referring to FIG. 1, the light-source 92 is assembled on the carriage top cover 93, and the condensing device 96 and the photoelectric transforming device 97 are screwed to an outside of the carriage bottom seat 95.
However, when the parts of the carriage module are assembled on the carriage top cover 93 or the carriage bottom seat 95, assembly tolerance occur during assembly of the carriage module. Then, the carriage top cover 93 and the carriage bottom seat 95 are assembled together, and the assembly tolerance occurs once again. The two assembly errors will affect the scanning quality. Furthermore, the carriage bottom seat 95 has a concave shape, which limits the assembly space of the carriage module.
With the employment of unique considerations and application of theories, and based on several years experience in specialized production of all flexible assembly systems and mechanisms, the inventor has come up with an innovative improved structure of the carriage module.